1. Technical Field
The present invention relates to an art for transferring a decorative layer on a three-dimensional design surface.
2. Background Art
There have been techniques for providing a three-dimensional design surface on a base body of a design member and plating a decorative layer on the design surface in order to provide a three-dimensional design to the design member. The decorative layer may be directly plated on the design surface, for example. Alternatively, a separate design member from the base body is provided, a three-dimensional decorative layer is plated, and the design member may be integrated into the base body. Also in this case, the design member having the three-dimensional decorative layer plated on the base body can be obtained.
In the case where the decorative layer is plated as mentioned above, an attractive three-dimensional decorative layer may be formed, and the design member that is superior in a design property can be obtained. In the case where the decorative layer may be plated, however, there is a problem that it will be difficult to reduce the manufacturing cost, because the product weight will increase and the mask process and the like will be necessary.
There has been a technique of using a transfer film and transferring the decorative layer onto the planer design surface (see Patent documents 1 and 2, for example). There has been a general transfer film, in which a transfer layer containing a decorative layer and a adhesive layer is laminated on the base film. Pressuring this type of transfer film against the design surface allows the decorative layer on the base film to be transferred onto the design surface. As a specific process, first, the adhesive layer contained in the transfer layer is heated to be softened or melted. Under this state, pressuring the transfer layer against the design surface causes the decorative layer contained in the transfer layer to be adhered onto the design surface by the adhesive layer. According to this process, it is considered that the manufacturing cost may be reduced compared to the case where the decorative layer is plated.
However, the general transfer film is of a planar type. Therefore, when the decorative layer is transferred onto the three-dimensionally shaped (that is, three-dimensional) design surface, it is necessary to fit the transfer film along the three-dimensional design surface. In fitting the planar transfer layer along the three-dimensional design surface, however, there is a case of causing the transfer layer to wrinkle or crack therein, which makes it difficult to obtain the design member having a superior design property.
Further, in order to evenly transfer the decorative layer to the entire decoration surface, the transfer film is required to be pressed hard against the entire design surface. However, when the design surface has a three-dimensional shape, for example, and the transfer film is pressed in one direction, while it is easy to cause the pressing force to work on the surface which is vertical to the pressing direction, it is difficult to cause the pressing force to work on the surface which is parallel to the pressing direction. Therefore, it is quite difficult to form the decorative layer with leas unevenness by the transferring, and the parting portion between the decorative layer and the portion other than the decorative layer on the base body is likely to be irregular. In other words, when the design surface of the base body has a three-dimensional shape, the parting property between the decorative layer and the portion other than the decorative layer is likely to be degenerated, which makes it difficult to obtain the design member superior in a design property.